Commercial Ionic Liquids Research Articles

Anodizing Tungsten Foil with Ionic Liquids for Enhanced Photoelectrochemical Applications.

This research examines the influence of adding a commercial ionic liquid to the electrolyte during the electrochemical anodization of tungsten for the fabrication of WO3 nanostructures for photoelectrochemical applications. An aqueous electrolyte composed of 1.5 M methanesulfonic acid and 5% v/v [BMIM][BF4] or [EMIM][BF4] was used. A nanostructure synthesized in an ionic-liquid-free electrolyte was taken as a reference. Morphological and structural studies of the nanostructures were performed via field emission scanning electron microscopy and X-ray diffraction analyses. Electrochemical characterization was carried out using electrochemical impedance spectroscopy and a Mott-Schottky analysis. From the results, it is highlighted that, by adding either of the two ionic liquids to the electrolyte, well-defined WO3 nanoplates with improved morphological, structural, and electrochemical properties are obtained compared to samples synthesized without ionic liquid. In order to evaluate their photoelectrocatalytic performance, the samples were used as photocatalysts to generate hydrogen by splitting water molecules and in the photoelectrochemical degradation of methyl red dye. In both applications, the nanostructures synthesized with the addition of either of the ionic liquids showed a better performance. These findings confirm the suitability of ionic liquids, such as [BMIM][BF4] and [EMIM][BF4], for the synthesis of highly efficient photoelectrocatalysts via electrochemical anodization.

Bipolar Electrochemical Analysis of Chirality in Complex Media through Miniaturized Stereoselective Light-Emitting Systems

Environmentally relevant contaminants endowed with chirality may include pharmaceutical compounds, flame retardants, perfluoroalkyl chemicals, pesticides, and polychlorinated biphenyls. Despite having similar physicochemical properties, enantiomers may differ in their biochemical interactions with enzymes, receptors, and other chiral molecules leading to different biological responses. In this work, we have designed a wireless miniaturized stereoselective light-emitting system able to qualitatively detect a chiral contaminant (3,4-dihydroxyphenylalanine, DOPA) dissolved in reduced volumes (in the microliters range), through bipolar electrochemistry. The diastereomeric environment was created by mixing the enantiomers of an inherently chiral inductor endowed with helical shape (7,8-dipropyltetrathia[7]helicene) and the chiral probe (DOPA) in micro-solutions of a commercial ionic liquid. The synergy between the inductor, the applied electric field, and the chiral pollutant was transduced by the light emission produced from a miniaturized light-emitting diode (LED) exploited in such an approach as a bipolar electrode.

Synthesis, biocompatibility, and antimicrobial properties of glucose-based ionic liquids

New carbohydrate-based ionic liquids are characterized, towards their thermal stability, biocompatibility and antimicrobial behavior. The results led to structure–property relationships and higher cell viabilities than most commercial ionic liquids.

Ionic liquid-doped liquid crystal/polymer composite for multifunctional smart windows

In this work, a facile approach to fabricating multifunctional smart windows by employing an ionic liquid-doped liquid crystal (LC)/polymer composite was reported. The composite was prepared via an established method of polymerization-induced phase separation while a commercial ionic liquid was doped into the composite as a supporting electrolyte. The smart window, which was prepared by sandwiching the as-prepared composite in two indium tin oxide (ITO) glasses, can exhibit a multifunctional mode. Specifically, the light transmittance and the coloration of the windows were regulated by different external stimuli. The electrically switchable transmittance of the window was achieved by an alternating current (AC) electric field and the window transformed into a transparent state from an opaque state under the AC field. The temperature was also used to realize the heat controllable transmittance, in which the window was turbid at a lower temperature and transparent at a high temperature. The electrically induced coloration of the window was manipulated by a direct current (DC) electric field and the window was changed into a green state from a colorless state under the DC field. This work is expected to open avenues to achieve a promising candidate for multifunctional smart windows with practical applications.

Acid and Base Water Coexists in a Micro‐Structured Ionic Liquid and Catalyzes Organic Reactions in One‐Pot

AbstractThe most paradigmatic example of antagonist chemical species are protons and hydroxyls, and their coexistence in a liquid system is of high interest. Here we show that commercial ionic liquids stabilize microdroplets of water with pH<0 and pH>14, concomitantly and without any additive, and that this micro‐structured liquid medium catalyzes organic reactions in one‐pot.

Electrically induced coloration of polymer-stabilized cholesteric liquid crystal films with broadband reflection capability for smart windows

In this work, a novel approach to realizing the electrically induced coloration of polymer-stabilized cholesteric liquid crystal (LC) films with broadband reflection capability for smart windows was reported. Only starting common materials and an established preparation method were used. The polymer-stabilized cholesteric LC films with broadband reflection capability were prepared via the method of polymerization-induced pitch gradient. After doping with a commercial ionic liquid which served as the supporting electrolyte in the system, the initial broadband reflection capability of the polymer-stabilized cholesteric LCs film was not damaged, and the film can change into a colored state from a colorless state under a low direct current (DC) voltage. The color of the polymer-stabilized cholesteric LCs also can gradually disappear after the removal of the field despite the slow response rate. The as-prepared polymer-stabilized cholesteric LCs in this work not only can be applied in the energy-saving smart windows and thermal management for buildings, but also presented the performance of electrically induced coloration under a low voltage. This work is expected to provide a creative approach for the preparation of electrochromic energy-saving smart windows.

Cation effect on bis(trifluoromethylsulfonyl)imide-based ionic liquids with triethylsulfonium, 1,2-dimethyl-3-propylimidazolium, 1-methyl-1-propylpyrrolidinium, and 1-butyl-2,3-dimethylimidazolium density at high pressure

In this work, cation effect on density for four commercial ionic liquids (ILs) based on bis(trifluoromethylsulfonyl) imide ([(CF3SO2)2N]) anion were determined at high pressure and high temperature (HPHT) at P = (0.20 to 100.00) MPa and T = (298.15 to 398.15) K, using the vibrating tube method. Triethylsulfonium ([S222]), 1,2-dimethyl-3-propylimidazolium ([C3C1C1Im]), 1-methyl-1-propylpyrrolidinium ([C3C1pyr]), and 1-butyl-2,3-dimethylimidazolium ([C4C1C1Im]) cations were combined with bis(trifluoromethylsulfonyl) imide ([(CF3SO2)2N]) anion to form four different ionic liquids. Density increases in the following order: [C4C1C1Im][(CF3SO2)2N] < [C3C1pyr][(CF3SO2)2N] < [C3C1C1Im][(CF3SO2)2N] < [S222][(CF3SO2)2N], in accordance to the packing effect. Experimental density data were correlated by using Tammann-Tait-type equation, with an average absolute relative deviation (%AARD) less than 0.0090 % for [S222][(CF3SO2)2N], [C3C1C1Im][(CF3SO2)2N], and [C4C1C1Im][(CF3SO2)2N], and less than 0.0150 % for [C3C1pyr][(CF3SO2)2N]. Furthermore, seven group contribution estimation methods were successfully used to density prediction for these ionic liquids. Finally, isothermal compressibility (κT), isobaric expansivity (αp), thermal pressure coefficient (γv), and internal pressure (Pi) were determined from these experimental data, showing their relationship with anion and cations structural packing effect.

Fluoride removal from natural waters by polymer inclusion membranes

A polymer inclusion membrane (PIM) containing commercial ionic liquid methyltrioctylammonium chloride (Aliquat 336) as a carrier and cellulose triacetate (CTA) as a base polymer has been used for the first time to remove fluoride from natural waters. Due to the anion-exchange characteristics of the carrier, a 1 M NaCl solution has been used as a receiving phase. It has been found that the addition of tributyl phosphate (TBP) in the formulation of the PIM increased the membrane's performance. Several parameters have been investigated using a PIM made of 30% CTA, 50% Aliquat 336, and 20% TBP (% in mass) including the effect of other ions such as chloride and sulphate and the effect of pH. Only when the feed phase contains high amounts of chloride (concentration 10 times higher than fluoride) a slight decrease on PIM's efficiency is observed (85% defluoridation). The separation system developed here has been used satisfactorily for fluoride removal from different naturally occurring waters. Moreover, the membrane's reusability has also been investigated, showing that the membrane can be used for four cycles without loss of efficiency in removing fluoride.

Photopolymerization of ionic liquids in flexible microporous aramids for ion conductive solid polyelectrolytes

This work presents the preparation of novel solid polymer electrolytes based on flexible microporous aramids filled with photopolymerized ionic liquids and lithium salt. The materials combined a high ionic conductivity with the mechanical and thermal characteristics of the aramids, including also good flexibility and handleability. First, a simple casting process was followed to obtain microporous aramids with an interconnected channel morphology. In a second step, this channel structure was filled with a solution of non-commercial photopolymerizable ionic liquid, commercial ionic liquids and the lithium salt, followed by UV irradiation to obtain the conducting aramids. Ionic conductivity of the materials was studied at 25 °C, and also in the temperature range between −50 to 90 °C, together with SEM analyses of the filled porous structure and thermal properties, to fully characterize the photopolymerization process of the ionic liquids inside the porous structure. The materials showed high ionic conductivity values together with excellent thermal and mechanical properties, indicating their viability as flexible and thermally stable solid electrolytes.

Study on the Intensification of Reaction Kinetics and Reactive Distillation for the Esterification of N-Butyl Acetate Using [HSO3-BMIM][HSO4] as a High-Efficiency Ionic Liquid Catalyst

An ionic liquid (IL) catalyst 1-sulfobutyl-3-methylimidazolium hydrogen sulfate, [HSO3-BMIM][HSO4], was used to produce n-butyl acetate (BuAc) via esterification. A novel modified nonideal homogeneous kinetic model was developed by self-catalysis theory. A new reactive distillation (RD) process using [HSO3-BMIM][HSO4] to produce BuAc was intensified using Aspen simulation taking advantage of phase splitting to increase the ester purity. Various design parameters like reactant feed location, reflux ratio, reactant feed molar ratio, flow ratio of products to materials, and condenser pressure were optimized. Fitting results indicated that modified models presented exact prediction results for the [HSO3-BMIM][HSO4]-catalyzed esterification compared with the unmodified model because the former introduced a revisional term for the self-catalysis of HAc, which revealed the mechanism of self-catalysis and interaction between ILs and reactants. The BuAc purity was increased from 91.05 to 95.02 wt % by the RD process intensification. [HSO3-BMIM][HSO4] showed a higher acid conversion (75%) than commercial ILs and resins. The ester yield was higher when using [HSO3-BMIM][HSO4] as the catalyst than resin A (80.89 wt %) in the intensified RD process. This research provides a novel modified method for the kinetic model in the IL-catalyzed reaction where the modified model exhibited a high accuracy and is useful for improving the production efficiency and controlling the catalyst dosage in the chemical engineering process design. The intensified RD process shows a flexible design for IL application, which is helpful for designing industrial scale-up.

A comparative study between ionic liquid coating and counterparts in bulk for toluene absorption

The structure-activity relationship (SAR) for toluene absorption and desorption in ionic liquids (ILs) has been investigated for seven commercial ILs in bulk and thin liquid layer. ILs with imidazolium cations of different alkyl chain lengths and a Hofmeister series of anions including [CH3COO], [I], [BF4], [HSO4], and [PF6] were included. Absorption capacity for toluene increases with increasing kosmotropicity of the cation and anion, while the absorption rate in bulk ILs is governed by viscosity and that in thin ILs layer by the oil-water partition coefficient (Kow). A regenerability coefficient (Rp) measures toluene desorption and IL regeneration. The release rate as measured by dRp/dt correlates well with the Kow and viscosity of the ILs and tx, the time required to completely desorb toluene is related to its ionic strength as measured from v(C2H) of the imidazolium cation. These properties are in turn governed by the kosmotropicity of the cation and anion pair forming the IL.

Sepiolite modified with phosphonium ionic liquids as anticorrosive pigment for epoxy coatings

The performance of sepiolite modified with different phosphonium-based ionic liquids (SepIL) as anti-corrosive pigment for epoxy resin (ER) coatings were discussed in this paper. The ionic liquids (IL) used to functionalize Sep clay mineral included trihexyl-(tetradecyl)phosphonium bistriflimide (IL1) and ethyl-tri(butyl)-phosphonium diethylphosphate (IL2) as commercial IL and the synthesized 11-carboxyundecyl-(triphenyl)-phosphonium bromide (IL3). All SepIL samples were characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), elemental analysis (CHN) and X-ray diffraction (XRD). The effect of the incorporation of Sep and SepIL on the rheological properties of the ER-based dispersions and on anticorrosion properties of epoxy networks cured with isophorone diamine was investigated. The ER-based coatings loaded with Sep modified with different ionic liquids presented enhanced the anticorrosive properties with outstanding barrier properties against the diffusion of the electrolyte solution, as indicated by electrochemical impedance spectroscopy (EIS). The superior corrosion resistance of ER loaded with SepIL was also kept with scratched coating, due to the inhibition activity of the ionic liquid against corrosion process.

Valorization of Cellulose Recovered from WWTP Sludge to Added Value Levulinic Acid with a Brønsted Acidic Ionic Liquid

The progressive decline of using fossil sources in the industry means that alternative resources must be found to produce chemicals. Waste biomass (sewage sludge) and waste lignocellulosic resources (food, forestry, or paper industries) are ideal candidates to take over from fossil sources. Municipal sewage sludge, and especially primary sludge, has a significant proportion of cellulose in its composition. Proper treatment of this cellulose allows the production of interesting chemicals like levulinic acid that are precursors (bio-blocks or building blocks) for other organic chemical processes. Cellulose was extracted from municipal wet primary sludge and paper industry dried sludge with a commercial ionic liquid. More than 99% of the cellulose has been recovered in both cases. Extraction was followed by the bleaching of the cellulose for its purification. In the bleaching, a large part of the ash was removed (up to 70% with municipal sludge). Finally, the purified cellulose was converted in levulinic acid by catalyzed hydrothermal liquefaction. The reaction, done at 170 °C and 7 bar, catalyzed by a tailored Brønsted acidic ionic liquid produced levulinic acid and other by-products in smaller quantities. The process had a conversion of cellulose to levulinic acid of 0.25 with municipal sludge and of 0.31 with industrial sludge. These results fully justify the process but, require further study to increase the conversion of cellulose to levulinic acid.

Application of protic ionic liquids in the microwave-assisted extraction of phycobiliproteins from Arthrospira platensis with antioxidant activity

Phycobiliproteins are potential molecules for use in various applications. Although phycobiliproteins extraction classical methods are reproducible and show good yields, they are generally time-consuming and require the use of high energy consumption and/or large volumes of solvent. Therefore, it is necessary the development of new eco-friendlier process by extraction techniques, permitting the transfer of the results obtained in laboratory scale for industrial. Then, microwave-assisted extraction using protic ionic liquid as solvent was proposed and optimized to extract phycobiliproteins from Arthrospira platensis in an efficient manner. The protic ionic liquids (PILs): 2-hydroxyethylammonium acetate (2-HEAA), 2-hydroxyethylammonium formate (2-HEAF), their equimolar mixture (2-HEAA + 2-HEAF), and the commercial ionic liquid 1-butyl-3-methylimidazolium chloride [Bmim]Cl were used as solvents, and sodium phosphate buffer as a control and the conditions of extraction were evaluated. The irradiation power was the most significant variable for the extraction process, and it showed a negative effect. The process conducted at 62 W and pH 7.0, using 2-HEAA + 2-HEAF and a solvent: biomass ratio of 10 mL∙g−1, showed the highest phycobiliproteins concentrations. The purity obtained for phycocyanin, allophycocyanin and phycoerythrin were 1.22, 1.03, and 0.71, respectively. The mixture of the PILs (2-HEAA + 2-HEAF) can be reused for three cycles for extraction of allophycocyanin. The extraction of phycobiliproteins using microwave and ionic liquids was efficient and the degree of purity and antioxidant activity achieved allows the application of these pigments in food and cosmetics.

Tuning thin-film composite reverse osmosis membranes using deep eutectic solvents and ionic liquids toward enhanced water permeation

Deep eutectic solvents (DES) have invoked an enormous interest as inexpensive, greener and biorenewable solvents and additives with promising applications. In the present study, we investigated a choline chloride-urea based DES and a series of commercial ionic liquids (ILs) as additives including 1-hexyl-3-methyl-imidazolium chloride, 3-methyl-1-octyl-imidazolium tetra fluoroborate, N-butyl pyridinium and betaine monohydrate to modify the polyamide (PA) layer of reverse osmosis (RO) membranes. The ILs were selected from various categories to find better of them in RO modification. Accordingly, the DES and ILs with different concentrations were added to the MPD aqueous solution. The results of SEM and AFM analyses showed a smoother surface for the DES and ILs-modified membranes. The membrane modified with 1 wt% of DES achieved the pure water flux of 56.7 L/m2h and the observed salt rejection of 96.4%, exhibiting a 27% and 3% increase in water flux and salt rejection, respectively, as compared with the unmodified membrane. Among the used ILs, the membranes modified with N-butyl pyridinium and betaine monohydrate showed the best desalination performance, with the pure water flux of 78.9 L/m2h and 51.7 L/m2h and the NaCl rejection of 97.3% and 94.4%, respectively. Also, choline hydroxide IL was used for the surface modification of the SO3H-g-C3N4 nanosheets to examine efficiency of ILs on membranes, when located on nanosheet surface. The results of the desalination experiments showed that the incorporation of the modified nanosheets at low concentrations was effective in enhancing the membrane performance. Although increasing the concentrations of nanosheets in the PA layer of the membranes resulted in the enhanced water flux, the salt rejection was decreased.

A highly sensitive ion selective electrochemical sensor amplified with ionic liquid for determination of lanthanum ion in real water samples

ABSTRACT Lanthanum(La) has been utilised in various industries and entered water samples through the discharge of industrial wastewater. Exposure to La (III) ion can damage some human organisms, such as the nervous system and lungs, and increase the risk of lung cancer. Therefore, the measurement of lanthanum in water samples is very important to control its adverse effects. In this study, a new and cheap potentiometric sensor was developed to determine La(III) ion in real water samples. A carbon paste electrode (CPEs) as an indicator electrode was prepared using graphite powder, commercial ionic liquids as a binder, graphene oxide and a synthetic ligand as an ionophore. The complex reaction between the 2-((2-(5-amino-1, 3, 4-thiadiazol-2-yl)hydrazono)methyl)phenol Schiff base and La(III) ion has been explored by employing the density functional theory (DFT). The results of the theoretical were shown the complex formation La(III) is thermodynamically favourable and confirmed the obtained experimental results. The percentage of components present in La(III) ion electrode was optimised by an experimental design based on D-optimal mixture design, which reduces the cost and time of the electrode optimisation process. A Nernstian behaviour was observed by the electrode in a concentration range from 7.0 × 10−7 to 1.0 × 10−1 M to measure La(III) with a correlation coefficient of 0.9832. Also, a low LODs (5.16 × 10−8) and RSDs (2.05%) were obtained with the sensor. Application of the sensor for the real samples was indicated the La(III) sensor can be well utilised for the analyte determination with a suitable recovery (≥97.4).

Ionogels at the Water-Energy Nexus for Desalination Powered by Ultralow-Grade Heat.

Industrial processes emit enormous amounts of waste heat below 40 °C into the environment as it is cannot be used in other processes. Adsorption desalination can be driven by low-grade heat but has never been proven at temperatures below 40 °C as current adsorption materials require heat sources of 50-150 °C. Here, we present the first experimental study on adsorption desalination using a novel class of ionogel adsorption materials, which can be regenerated at 25 °C or a driving temperature difference of 5 °C. This outstanding property contrasts with the benchmarking silica gel, which requires heat sources of at least 50 °C. Ionogels are solid-state ionic materials retaining the sorption properties of the constituent ionic liquid. Thermodynamic vapor-liquid equilibrium data of water sorption on commercial ionic liquids reveal 1-ethyl-3-methylimidazolium acetate as the best fluid for this specific application. A full experimental characterization of the material is performed from imaging at the nanoscale to testing on a real adsorption desalinator. At 25 °C, the material achieves a specific daily water production of 6.7 kgwater/(kgionogel d), increasing to 17.5 kgwater/(kgionogeld) at 45 °C, outperforming silica gel by a factor of 2.

Elimination of carcinogenic chromium(VI) by reduction at two-phase system

The novel complexing agent (N,N-dihexyl-N′-hydroxypyridine-2-carboximidamide) and commercial ionic liquid (Aliquat®336) were used as Cr(VI) reducers, in order to eliminate carcinogenic chromium from aqueous solutions. To set an optimum condition allowing to the efficient Cr(VI) reduction, various factors, like effect of pH, contact time, Cr(VI) concentration, were examined. It was shown, that regardless on the used compounds, the conducting of the experiments at pH of 0 results in 100% Cr(VI) reduction, and the reactions follow a first-order kinetic. Moreover, the using of N,N-dihexyl-N′-hydroxypyridine-2-carboximidamide, the reduction was very fast, and required just 1 min shaking. The studies of changes in the Aliquat®336 structure indicated that the ionic liquid compounds degraded to tertiary amine (mechanism according to the rearrangement generates the protonated dialkylhydroxyamine), while DH2PIA proceeded through the iminoxy specie, which undergone either hydrogen atom abstraction allowing for regeneration of DH2PIA.

Evaluation of different ionic liquid stationary phases for the analysis of carbohydrates by gas chromatography-mass spectrometry.

Five commercial ionic liquid (IL) columns have been evaluated for the first time for the gas chromatography-mass spectrometry (GC-MS) analysis of low molecular weight carbohydrate (LMWC) standards (mono-, di-, and trisaccharides, inositols, and iminosugars). A previous derivatization step was necessary to convert the LMWCs into their volatile and stable derivatives. Compared with conventional GC stationary phases, such as HP-1 and Supelcowax® 10, IL columns have shown a different selectivity in the separation of target compounds. Among the IL columns, only SLB™-IL82 allowed the elution of all the LMWCs studied. Its performance in terms of peak width and asymmetry, evaluated under different oven temperature conditions, was shown to be dependent on the carbohydrate class considered. As an example of application, a SLB™-IL82 column was successfully used to separate the complex mixtures of LMWCs in hyacinth and mulberry extracts. This column is an interesting alternative to the conventional stationary phases used in the GC analysis of LMWCs in real-world samples. Graphical abstract.

Development of novel hydrophilic ionic liquid membranes for the recovery of biobutanol through pervaporation

This paper aims to develop novel hydrophilic ionic liquid membranes using pervaporation for the recovery of biobutanol. Multiple polyvinyl alcohol (PVA) membranes based on three commercial ionic liquids with different loading were prepared for various experimental trials. The ionic liquids selected for the study include tributyl (tetradecyl) phosphonium chloride ([TBTDP][Cl]), tetrabutyl phosphonium bromide ([TBP][Br]) and tributyl methyl phosphonium methylsulphate ([TBMP][MS]). The synthesized membranes were characterized and tested in a custom-built pervaporation set-up. All ionic liquid membranes showed better results with total flux of 1.58 kg/m2h, 1.43 kg/m2h, 1.38 kg/m2h at 30% loading of [TBP][Br], [TBMP][MS] and [TBTDP][Cl] respectively. The comparison of ionic liquid membranes revealed that by incorporating [TBMP]MS to PVA matrix resulted in a maximum separation factor of 147 at 30 wt% loading combined with a relatively higher total flux of 1.43 kg/m2h. Density functional theory (DFT) calculations were also carried out to evaluate the experimental observations along with theoretical studies. The improved permeation properties make these phosphonium based ionic liquid a promising additive in PVA matrix for butanol-water separation under varying temperature conditions.